This invention relates to a hinge device for inclined tiltable windows with external upper and lower cover rails which are secured to the main frame of the window and to its sash, respectively, and in the closing position of the window overlap each other in the area of the tilting axis of the sash, said hinge device being of the known type comprising two base plates adapted to be secured to the main frame of the window and to its sash, respectively, and an intermediate member inserted between said base plates and with which the sash base plate is tiltably connected through a pivot pin, said intermediate member being connected through a pair of pivotable links in a parallelogramlike manner with the base plate of the main frame so as to cause the upper end portion of the cover rail of the window sash, during initial tilting thereof in the opening direction to be downwardly displaced along the underside of the lower end portion of the main frame cover rail to get clear thereof so as to allow further tilting or rotation of the sash, and means for coordinating the rotation of the sash base plate about the pivot pin in relation to the intermediate member with the parallelogramlike movement of this member in relation to the base plate of the main frame.
A hinge device of said kind is disclosed in the specification of Danish Patent Application No. 2904/79 (corresponding to e.g. U.S. Ser. No. 159,462 filed June 16, 1980, now U.S. Pat. No. 4,366,597), according to which the structure includes a guide pin which is responsible for the coordination of the mainly translatory displacement of the intermediate member and the tilting or rotation of the sash hinge part about the pivot pin. Said guide pin is usually fixed to the base plate of the sash part of the hinge and cooperates, on the one hand, with the concave side of an arc-shaped guide member on the base plate of the main frame hinge part and, on the other hand, with an opposite edge provided on one of the pivotable links associated with the intermediate member. A condition of a perfect function of such a structure is that the guide pin slides sufficiently easily between the guide member and the edge, as a clumsy closing of the window sash would otherwise cause the guide pin to get jammed, following which an increased force exerted on the sash might cause damage to the hinge. Moreover, it may be considered to constitute an undesired complication of the prior hinge device that the base plates of said two hinge parts must be provided with cooperating guide cams which become operative when said guide pin at the transition from the initial opening of the sash till its rotation about the pivot pin gets clear of the associated guide surfaces of the hinge part.